Table 1: Demographic and clinical characteristics.

Characteristic Value

Number of patients206
Sex
 Male115 (55.8%)
 Female91 (44.2%)
Age (year)61.0 ± 12.9
Months of follow-up
 Imaging40.7 ± 19.7
 Clinical 51.1 ± 20.8
Number of instrumented levels
 1 level86 (41.7%)
  L2-32
  L3-47
  L4-561
  L5-S116
 2 levels120 (58.3%)
  L2-3-44
  L3-4-586
  L4-5-S130

Values are presented by mean ± SD.